Lens assembly

Abstract

A lens assembly includes a first lens, a second lens, a third lens, a fourth, a fifth lens, a sixth lens, a seventh lens, and an eighth lens. The first lens is a meniscus lens with refractive power. The second lens is a meniscus lens with positive refractive power and includes a convex surface facing an object side and a concave surface facing an image side. The third lens is with refractive power. The fourth lens is with positive refractive power and includes a convex surface facing the image side. The fifth lens is with refractive power. The sixth lens is with positive refractive power. The seventh lens is with refractive power. The eighth lens is with refractive power. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are arranged in order from the object side to the image side along an optical axis.

Description

[Technical Field]

[0001] This invention relates to an imaging lens. [Previous Technology]

[0002] The current development trend of imaging lenses is not only towards miniaturization, but also requires high resolution due to different application needs. Conventional imaging lenses can no longer meet the current needs, and a new imaging lens architecture is needed to simultaneously meet the requirements of miniaturization and high resolution. [Summary of the Invention]

[0003] In view of this, the main objective of the present invention is to provide an imaging lens that has a shorter total length and higher resolution, but still has good optical performance.

[0004] The present invention provides an imaging lens comprising a first lens, a second lens, a third lens, a fourth lens, a fifth lens, a sixth lens, a seventh lens, and an eighth lens. The first lens is a meniscus lens with refractive power. The second lens is a meniscus lens with positive refractive power, and includes a convex surface facing an object side and a concave surface facing an image side. The third lens has refractive power. The fourth lens has positive refractive power and includes a convex surface facing the image side. The fifth lens has refractive power. The sixth lens has positive refractive power. The seventh lens has refractive power. The eighth lens has refractive power. The first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are arranged sequentially along an optical axis from the object side to the image side. The imaging lens satisfies at least one of the following conditions: 4TTL / f4.8; 0.1T23 / CT30.5; 2f2 / f2.5; 3(R21+R22) / f210; 1.7f4 / f2.5; 0.3(R61+R62) / f60.9; 1.2f2 / f61.8; 1.2f4 / f62; where TTL is the distance on the optical axis from the object-side surface of the first lens to the imaging plane, and T23 is the distance on the optical axis from the image-side surface of the second lens to the object-side surface of the third lens. Air gap, CT3 is the distance on the optical axis from the object side of the third lens to the image side of the third lens, f is the effective focal length of the imaging lens, f2 is the effective focal length of the second lens, f4 is the effective focal length of the fourth lens, f6 is the effective focal length of the sixth lens, R21 is the radius of curvature of the object side of the second lens, R22 is the radius of curvature of the image side of the second lens, R61 is the radius of curvature of the object side of the sixth lens, and R62 is the radius of curvature of the image side of the sixth lens.

[0005] The first lens has negative refractive power; the fifth lens has positive refractive power; the seventh lens has negative refractive power; and the eighth lens has positive refractive power.

[0006] The third lens has negative refractive power and includes a concave surface facing the object; and the seventh lens includes a concave surface facing the object.

[0007] The fifth lens includes a convex surface facing the object; the sixth lens includes a convex surface facing the object; and the seventh lens includes a convex surface facing the object.

[0008] The first lens includes a convex surface facing the object side and a concave surface facing the image side.

[0009] The third lens is a biconcave lens and may further include a concave surface facing the image side; and the seventh lens is a biconcave lens and may further include a concave surface facing the image side.

[0010] The fifth lens is a biconvex lens and may further include a convex surface facing the image side; the sixth lens is a biconvex lens and may further include a convex surface facing the image side; and the eighth lens is a biconvex lens and may further include a convex surface facing the image side.

[0011] The fourth lens is a biconvex lens, and may further include a convex surface facing the object.

[0012] The fourth lens is a meniscus lens and may further include a concave surface facing the object.

[0013] The imaging lens satisfies at least one of the following conditions: 3.5TTL / BFL 4.5; 0.9f2 / f4 1.3; wherein TTL is the distance from the object side of the first lens to the imaging surface on the optical axis, BFL is the distance from the image side of the eighth lens to the imaging surface on the optical axis, f2 is the effective focal length of the second lens, and f4 is the effective focal length of the fourth lens.

[0014] In order to make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, preferred embodiments are described in detail below with reference to the accompanying drawings. [Simplified Explanation of the Diagram]

[0066] Figure 1 is a schematic diagram of the lens configuration and optical path of an imaging lens according to a first embodiment of the present invention.

[0067] Figures 2 and 3 are respectively the field curvature diagram, distortion diagram, and spot diagram of the imaging lens according to the first embodiment of the present invention.

[0068] Figure 4 is a schematic diagram of the lens configuration and optical path of the imaging lens according to the second embodiment of the present invention.

[0069] Figures 5 and 6 are field curvature diagram, distortion diagram, and spot diagram of the imaging lens according to the second embodiment of the present invention, respectively.

[0070] Figure 7 is a schematic diagram of the lens configuration and optical path of the imaging lens according to the third embodiment of the present invention.

[0071] Figures 8 and 9 are field curvature diagram, distortion diagram, and spot diagram of the imaging lens according to the third embodiment of the present invention, respectively.

Implementation Method

[0015] The present invention provides an imaging lens, comprising: a first lens, the first lens being a meniscus lens having refractive power; a second lens, the second lens being a meniscus lens having positive refractive power, the second lens including a convex surface facing an object side and a concave surface facing an image side; a third lens, the third lens having refractive power; a fourth lens, the fourth lens having positive refractive power, the fourth lens including a convex surface facing the image side; a fifth lens, the fifth lens having refractive power; a sixth lens, the sixth lens having positive refractive power; a seventh lens, the seventh lens having refractive power; and an eighth lens, the eighth lens having refractive power; wherein the first lens, the second lens, the third lens, the fourth lens, the fifth lens, the sixth lens, the seventh lens, and the eighth lens are arranged sequentially along an optical axis from the object side to the image side; wherein the imaging lens satisfies at least one of the following conditions: 4TTL / f4.8; 0.1T23 / CT30. 5; 2f2 / f2.5; 3(R21+R22) / f210; 1.7f4 / f2.5; 0.3(R61+R62) / f60.9; 1.2f2 / f61.8; 1.2f4 / f62; where TTL is the distance from the object side of the first lens to the imaging plane on the optical axis, T23 is the air gap from the image side of the second lens to the object side of the third lens on the optical axis, and CT3 is the distance from the object side of the third lens to the image plane on the optical axis. The distance between the image-side surface of the third lens and the optical axis is given by f, where f is an effective focal length of the imaging lens, f2 is an effective focal length of the second lens, f4 is an effective focal length of the fourth lens, f6 is an effective focal length of the sixth lens, R21 is a radius of curvature of the object-side surface of the second lens, R22 is a radius of curvature of the image-side surface of the second lens, R61 is a radius of curvature of the object-side surface of the sixth lens, and R62 is a radius of curvature of the image-side surface of the sixth lens. When the imaging lens of the present invention satisfies the above features and at least one of the above conditions, and no other additional features or conditions are required, the basic operation of the imaging lens of the present invention can be achieved.

[0016] Please refer to Tables 1, 3 and 5 below, where Tables 1, 3 and 5 are respectively the relevant parameter tables of each lens of the first to third embodiments of the imaging lens according to the present invention.

[0017] Figures 1, 4, and 7 are schematic diagrams of lens configuration and optical path according to the first, second, and third embodiments of the imaging lens of the present invention. The first lenses L11, L21, and L31 are meniscus lenses with negative refractive power, made of glass, with their object-side surfaces S11, S21, and S31 being convex and their image-side surfaces S12, S22, and S32 being concave. The object-side surfaces S11, S21, and S31 and the image-side surfaces S12, S22, and S32 are all spherical surfaces.

[0018] The second lenses L12, L22, and L32 are meniscus lenses with positive refractive power. They are made of glass. Their object-side surfaces S13, S23, and S33 are convex, and their image-side surfaces S14, S24, and S34 are concave. Both the object-side surfaces S13, S23, and S33 and the image-side surfaces S14, S24, and S34 are spherical surfaces.

[0019] The third lenses L13, L23, and L33 are biconcave lenses with negative refractive power. They are made of glass. Their object-side surfaces S15, S25, and S35 are concave, and their image-side surfaces S16, S26, and S36 are concave. Both the object-side surfaces S15, S25, and S35 and the image-side surfaces S16, S26, and S36 are spherical surfaces.

[0020] The fourth lens L14, L24, L34 has positive refractive power and is made of glass. Its image side surface S18, S28, S38 is convex, and its object side surface S17, S27, S37 and image side surface S18, S28, S38 are all spherical surfaces.

[0021] The fifth lenses L15, L25, and L35 are biconvex lenses with positive refractive power. They are made of glass. Their object-side surfaces S110, S210, and S310 are convex, and their image-side surfaces S111, S211, and S311 are convex. Both the object-side surfaces S110, S210, and S310 and the image-side surfaces S111, S211, and S311 are spherical surfaces.

[0022] The sixth lenses L16, L26, and L36 are biconvex lenses with positive refractive power. They are made of glass. Their object-side surfaces S112, S212, and S312 are convex, and their image-side surfaces S113, S213, and S313 are convex. Both the object-side surfaces S112, S212, and S312 and the image-side surfaces S113, S213, and S313 are spherical surfaces.

[0023] The seventh lenses L17, L27, and L37 are biconcave lenses with negative refractive power. They are made of glass. Their object-side surfaces S114, S214, and S314 are concave, and their image-side surfaces S115, S215, and S315 are concave. Both the object-side surfaces S114, S214, and S314 and the image-side surfaces S115, S215, and S315 are spherical surfaces.

[0024] The eighth lenses L18, L28, and L38 are biconvex lenses with positive refractive power. They are made of glass. Their object-side surfaces S116, S216, and S316 are convex, and their image-side surfaces S117, S217, and S317 are convex. Both the object-side surfaces S116, S216, and S316 and the image-side surfaces S117, S217, and S317 are spherical surfaces.

[0025] In addition, imaging lenses 1, 2, and 3 satisfy at least one of the following conditions (1) to (10):

[0026] 4TTL / f4.8; (1)

[0027] 2f2 / f2.5; (2)

[0028] 1.7f4 / f2.5; (3)

[0029] 3(R21+R22) / f210; (4)

[0030] 0.3(R61+R62) / f60.9; (5)

[0031] 0.1T23 / CT30.5; (6)

[0032] 3.5TTL / BFL4.5; (7)

[0033] 1.2f2 / f61.8; (8)

[0034] 0.9f2 / f41.3; (9)

[0035] 1.2f4 / f62; (10)

[0036] Wherein, f is the effective focal length of one of the imaging lenses 1, 2, and 3 in the first to third embodiments; f2 is the effective focal length of one of the second lenses L12, L22, and L32 in the first to third embodiments; f4 is the effective focal length of one of the fourth lenses L14, L24, and L34 in the first to third embodiments; f6 is the effective focal length of one of the sixth lenses L16, L26, and L36 in the first to third embodiments; and TTL is the effective focal length of the first lenses L11, L21, and L3 in the first to third embodiments. The distance from the object sides S11, S21, S31 of lens 1 to the imaging surfaces IMA1, IMA2, IMA3 on the optical axes OA1, OA2, OA3; BFL is the distance from the image sides S117, S217, S317 of the eighth lens L18, L28, L38 to the imaging surfaces IMA1, IMA2, IMA3 on the optical axes OA1, OA2, OA3 in the first to third embodiments; R21 is the distance from the object sides S13, S23, S317 of the second lens L12, L22, L32 in the first to third embodiments. R22 is one of the curvature radii of the image sides S14, S24, and S34 of the second lenses L12, L22, and L32 in the first to third embodiments; R61 is one of the curvature radii of the object sides S112, S212, and S312 of the sixth lenses L16, L26, and L36 in the first to third embodiments; R62 is one of the curvature radii of the image sides S113, S213, and S313 of the sixth lenses L16, L26, and L36 in the first to third embodiments; T23 is one of the curvature radii of the image sides S14, S24, and S34 of the second lenses L12, L22, and L32 in the first to third embodiments; and T23 is one of the curvature radii of the image sides S14, S24, and S34 of the second lenses L12, L22, and L32 in the first to third embodiments. In the embodiments, the air gap between the image-side surfaces S14, S24, and S34 of the second lenses L12, L22, and L32 and the object-side surfaces S15, S25, and S35 of the third lenses L13, L23, and L33 on the optical axes OA1, OA2, and OA3, and CT3 in the first to third embodiments, the air gap between the object-side surfaces S15, S25, and S35 of the third lenses L13, L23, and L33 and the image-side surfaces S16, S26, and S36 of the third lenses L13, L23, and L33 on the optical axes OA1, OA2, and OA3, respectively. This allows the imaging lenses 1, 2, and 3 to effectively shorten the overall length of the lenses, effectively improve the resolution, and effectively correct aberrations.

[0037] When condition (1) is met: 4TTL / f4.8, the total length of the lens can be effectively shortened, resulting in a better miniaturized configuration and a reasonable back focal length. When condition (2) is met: 2f2 / f2.5, the field curvature caused by the first lens can be effectively corrected. When condition (3) is met: 1.7f4 / f2.5, aberrations can be effectively corrected. When condition (4) is met: 3(R21+R22) / f210, the surface shape and refractive power of the second lens can be effectively adjusted. When condition (5) is met: 0.3(R61+R62) / f60.9, the surface shape and refractive power of the sixth lens can be effectively adjusted. When condition (6) is met: 0.1T23 / CT30.5, the spacing and focusing ratio between the third and second lenses can be effectively adjusted, while further adjusting the optical path to prevent sharp bending and improving the yield of lens manufacturing and assembly. When condition (7) is met: 3.5TTL / BFL4.5, the total length of the lens and the back focal length can be effectively controlled within a certain ratio to obtain suitable assembly conditions, so as not to cause other problems in assembly due to the excessively short back focal length, such as dust or ghosting. When condition (8) is met: 1.2f2 / f61.8, condition (9) is met: 0.9f2 / f41.3, or condition (10) is met: 1.2f4 / f62, the refractive power distribution of the second and fourth lenses in front of the aperture and the sixth lens behind the aperture can be effectively balanced. At the same time, the second and fourth lenses have positive refractive power, which also reduces or balances the excessive negative refractive power of the first and third lenses.

[0038] The first embodiment of the imaging lens of the present invention will now be described in detail. Referring to Figure 1, the imaging lens 1 includes, along an optical axis OA1 from the object side to the image side, a first lens L11, a second lens L12, a third lens L13, a fourth lens L14, an aperture ST1, a fifth lens L15, a sixth lens L16, a seventh lens L17, an eighth lens L18, a filter OF1, and a protective glass CG1. During imaging, the light from the object side is finally imaged onto an imaging surface IMA1. According to paragraphs 1 to 10 of the [Implementation Method], wherein: the fourth lens L14 is a biconvex lens and its object side S17 is a convex surface; the filter OF1 has both its object side S118 and image side S119 as flat surfaces; the protective glass CG1 has both its object side S120 and image side S121 as flat surfaces; by utilizing the above-mentioned lens, aperture ST1 and the design that satisfies at least one of conditions (1) to (10), the imaging lens 1 can effectively shorten the total length of the lens, effectively improve the resolution, and effectively correct aberrations.

[0039] Table 1 is a table of relevant parameters of each lens of imaging lens 1 in Figure 1.

[0040]

[0041] Table 2 shows the relevant parameter values ​​of the imaging lens 1 of the first embodiment and the calculated values ​​of the corresponding conditions (1) to (10). As can be seen from Table 2, the imaging lens 1 of the first embodiment can meet the requirements of conditions (1) to (10).

[0042]

[0043] The imaging lens 1 of the first embodiment described above satisfies conditions (1) to (10) and the refractive power and surface shape in Table 1, and is a preferred embodiment of the present invention.

[0044] The imaging lens 1 of the first embodiment described above can also be modified to satisfy any one of the conditions (1) to (10) and that the first lens is a meniscus lens, the second lens is a meniscus lens with positive refractive power, the third lens has negative refractive power, the fourth lens has positive refractive power, the fifth lens has refractive power, the sixth lens has positive refractive power, the seventh lens has refractive power, and the eighth lens has refractive power. No other additional conditions or features are required to achieve the basic operation of the imaging lens of the present invention.

[0045] In addition, the optical performance of the imaging lens 1 in the first embodiment also meets the requirements. As can be seen from Figure 2, the field curvature of the imaging lens 1 in the first embodiment is between -0.04 mm and 0.04 mm, and its distortion is between -12% and 0%. As shown in Figure 3, the imaging lens 1 of the first embodiment has the following characteristics: when the image height is 0.000mm, the root mean square radius of the light spot is 0.595μm and the geometrical radius is 1.939μm; when the image height is 0.891mm, the root mean square radius is 0.713μm and the geometrical radius is 2.616μm; when the image height is 1.783mm, the root mean square radius is 0.973μm and the geometrical radius is 2.997μm; when the image height is 2.674mm, the root mean square radius is 1.796μm and the geometrical radius is 7.292μm; and when the image height is 3.566mm, the root mean square radius is 4.389μm and the geometrical radius is 16.172μm. It is evident that the field curvature and distortion of the imaging lens 1 in the first embodiment can be effectively corrected, thereby obtaining better optical performance.

[0046] The second embodiment of the imaging lens of the present invention will now be described in detail. Referring to Figure 4, the imaging lens 2, along an optical axis OA2 from the object side to the image side, sequentially includes a first lens L21, a second lens L22, a third lens L23, a fourth lens L24, an aperture ST2, a fifth lens L25, a sixth lens L26, a seventh lens L27, an eighth lens L28, a filter OF2, and a protective glass CG2. During imaging, the light from the object side is finally imaged onto an imaging surface IMA2. According to paragraphs 1 to 10 of the [Implementation Method], the fourth lens L24 is a meniscus lens with its object side S27 being concave; the filter OF2 has its object side S218 and image side S219 both being planar; the protective glass CG2 has its object side S220 and image side S221 both being planar; by utilizing the above-mentioned lens, aperture ST2 and the design that satisfies at least one of conditions (1) to (10), the imaging lens 2 can effectively shorten the total length of the lens, effectively improve the resolution, and effectively correct aberrations.

[0047] Table 3 is a table of relevant parameters for each lens of imaging lens 2 in Figure 4.

[0048]

[0049]

[0050] Table 4 shows the relevant parameter values ​​of the imaging lens 2 of the second embodiment and the calculated values ​​of the corresponding conditions (1) to (10). As can be seen from Table 4, the imaging lens 2 of the second embodiment can meet the requirements of conditions (1) to (10).

[0051]

[0052] The imaging lens 2 of the second embodiment described above satisfies conditions (1) to (10) and the refractive power and surface shape in Table 3, and is a preferred embodiment of the present invention.

[0053] The imaging lens 2 of the second embodiment described above can also be modified to satisfy any one of the conditions (1) to (10) and that the first lens is a meniscus lens, the second lens is a meniscus lens with positive refractive power, the third lens has negative refractive power, the fourth lens has positive refractive power, the fifth lens has refractive power, the sixth lens has positive refractive power, the seventh lens has refractive power, and the eighth lens has refractive power. No other additional conditions or features are required to achieve the basic operation of the imaging lens of the present invention.

[0054] Furthermore, the optical performance of the imaging lens 2 in the second embodiment also meets the requirements. As can be seen from Figure 5, the field curvature of the imaging lens 2 in the second embodiment is between -0.04 mm and 0.04 mm, and its distortion is between -12% and 0%. As shown in Figure 6, the imaging lens 2 of the second embodiment has the following characteristics: when the image height is 0.000mm, the root mean square radius of the light spot is 0.668μm and the geometric radius of the light spot is 2.252μm; when the image height is 0.891mm, the root mean square radius of the light spot is 0.833μm and the geometric radius of the light spot is 3.588μm; when the image height is 1.783mm, the root mean square radius of the light spot is 1.050μm and the geometric radius of the light spot is 3.535μm; when the image height is 2.674mm, the root mean square radius of the light spot is 1.777μm and the geometric radius of the light spot is 6.413μm; and when the image height is 3.566mm, the root mean square radius of the light spot is 5.326μm and the geometric radius of the light spot is 18.330μm. It is evident that the field curvature and distortion of the imaging lens 2 in the second embodiment can be effectively corrected, thereby obtaining better optical performance.

[0055] The third embodiment of the imaging lens of the present invention will now be described in detail. Referring to Figure 7, the imaging lens 3, along an optical axis OA3 from the object side to the image side, sequentially includes a first lens L31, a second lens L32, a third lens L33, a fourth lens L34, an aperture ST3, a fifth lens L35, a sixth lens L36, a seventh lens L37, an eighth lens L38, a filter OF3, and a protective glass CG3. During imaging, the light from the object side is finally imaged onto an imaging surface IMA3. According to paragraphs 1 to 10 of the [Implementation Method], the fourth lens L34 is a biconvex lens with its object side S37 being convex; the filter OF3 has its object side S318 and image side S319 both being planar; the protective glass CG3 has its object side S320 and image side S321 both being planar; by utilizing the above-mentioned lens, aperture ST3 and the design that satisfies at least one of conditions (1) to (10), the imaging lens 3 can effectively shorten the total length of the lens, effectively improve the resolution, and effectively correct aberrations.

[0056] Table 5 is a table of relevant parameters for each lens of imaging lens 3 in Figure 7.

[0057]

[0058]

[0059] Table 6 shows the relevant parameter values ​​of the imaging lens 3 of the third embodiment and the calculated values ​​of the corresponding conditions (1) to (10). As can be seen from Table 6, the imaging lens 3 of the third embodiment can meet the requirements of conditions (1) to (10).

[0060]

[0061] The imaging lens 3 of the third embodiment described above satisfies conditions (1) to (10) and the refractive power and surface shape in Table 5, and is a preferred embodiment of the present invention.

[0062] The imaging lens 3 of the third embodiment described above can also be modified to satisfy any one of the conditions (1) to (10) and that the first lens is a meniscus lens, the second lens is a meniscus lens with positive refractive power, the third lens has negative refractive power, the fourth lens has positive refractive power, the fifth lens has refractive power, the sixth lens has positive refractive power, the seventh lens has refractive power, and the eighth lens has refractive power. No other additional conditions or features are required to achieve the basic operation of the imaging lens of the present invention.

[0063] Furthermore, the optical performance of the imaging lens 3 in the third embodiment also meets the requirements. As can be seen from Figure 8, the field curvature of the imaging lens 3 in the third embodiment is between -0.04 mm and 0.04 mm, and its distortion is between -12% and 0%. As shown in Figure 6, the imaging lens 3 of the third embodiment has the following characteristics: when the image height is 0.000mm, the root mean square radius of the light spot is 0.584μm and the geometric radius of the light spot is 1.780μm; when the image height is 0.891mm, the root mean square radius of the light spot is 0.743μm and the geometric radius of the light spot is 2.810μm; when the image height is 1.783mm, the root mean square radius of the light spot is 1.067μm and the geometric radius of the light spot is 3.653μm; when the image height is 2.674mm, the root mean square radius of the light spot is 2.025μm and the geometric radius of the light spot is 8.773μm; and when the image height is 3.566mm, the root mean square radius of the light spot is 4.923μm and the geometric radius of the light spot is 17.372μm. It is evident that the field curvature and distortion of the imaging lens 3 in the third embodiment can be effectively corrected, thereby obtaining better optical performance.

[0064] Although the present invention has been disclosed above with reference to preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art may make various modifications and alterations without departing from the spirit and scope of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. An imaging lens, comprising: A first lens, which is a meniscus lens and has refractive power; a second lens, which is a meniscus lens and has positive refractive power, the second lens including a convex surface facing an object side and a concave surface facing an image side; a third lens, which has refractive power; and a fourth lens, which has positive refractive power, the fourth lens including a convex surface facing the image side. A fifth lens having positive refractive power; a sixth lens having positive refractive power; a seventh lens having refractive power; and an eighth lens having positive refractive power; wherein the first, second, third, fourth, fifth, sixth, seventh, and eighth lenses are arranged sequentially along an optical axis from the object side to the image side; wherein only eight lenses have refractive power; wherein the imaging lens satisfies at least one of the following conditions: 4TTL / f4.8; 2f2 / f2.5; 3(R21+R22) / f210; 1.7f4 / f2.5; 0.3(R61+R62) / f60.9; 1.2f2 / f6 1.8; 1.2f4 / f6 2; 3.5TTL / BFL 4.5; 0.9f2 / f4 1.3; where TTL is the distance on the optical axis from the object side of the first lens to the imaging plane, f is the effective focal length of the imaging lens, f2 is the effective focal length of the second lens, f4 is the effective focal length of the fourth lens, f6 is the effective focal length of the sixth lens, R21 is the radius of curvature of the object side of the second lens, R22 is the radius of curvature of the image side of the second lens, R61 is the radius of curvature of the object side of the sixth lens, R62 is the radius of curvature of the image side of the sixth lens, and BFL is the distance on the optical axis from the image side of the eighth lens to the imaging plane.

2. The imaging lens as described in claim 1, wherein: The first lens has negative refractive power; and the seventh lens has negative refractive power.

3. The imaging lens as described in claim 2, wherein: The third lens has negative refractive power and includes a concave surface facing the object; and the seventh lens includes a concave surface facing the object.

4. The imaging lens as described in claim 3, wherein: The fifth lens includes a convex surface facing the object side; the sixth lens includes a convex surface facing the object side; and the eighth lens includes a convex surface facing the object side.

5. The imaging lens as described in claim 4, wherein: The first lens includes a convex surface facing the object side and a concave surface facing the image side.

6. The imaging lens as described in claim 5, wherein: the third lens is a biconcave lens and further includes a concave surface facing the image side; and the seventh lens is a biconcave lens and further includes a concave surface facing the image side.

7. The imaging lens as described in claim 6, wherein: The fifth lens is a biconvex lens and further includes a convex surface facing the image side; the sixth lens is a biconvex lens and further includes a convex surface facing the image side; and the eighth lens is a biconvex lens and further includes a convex surface facing the image side.

8. The imaging lens as described in claim 7, wherein the fourth lens is a biconvex lens and further includes a convex surface facing the object side.

9. The imaging lens as described in claim 7, wherein the fourth lens is a meniscus lens and further includes a concave surface facing the object side.

10. An imaging lens as described in any one of claims 1 to 9 of the patent application, wherein the imaging lens satisfies the following conditions: 0.1T23 / CT30.5; where, T23 is an air gap on the optical axis between the image side of the second lens and the object side of the third lens, and CT3 is a gap on the optical axis between the object side of the third lens and the image side of the third lens.

Images